Tunned the structure and magnetic characteristics of noble metal (Pd)-doped Ba-Sr nanohexaferrites

In this study, various ratios of Pd-doped Ba-Sr nanohexaferrites (NHFs) were studied. All samples were produced via sol–gel combustion and were designated as Ba_0.5Sr_0.5Pd_3xFe_12-2xO₁₉ (x ≤ 0.1) NHFs. Detailed examinations of the magnetic and structural features were conducted. X-ray diffraction (XRD) confirmed the presence of a M-type HF phase, along with a small phase of iron oxide (Fe₂O₃) for some doping ratios. Both the SEM and TEM (Scanning and Transmission electron microscope respectively) revealed the formation of the hexagonal platelet morphology. The hyperfine parameters were determined by using Mössbauer spectroscopy. Pd²⁺ ions substituted Fe³⁺ ions at 12k site. The crystal symmetry not influenced by substitution. Fe³⁺ charge state was detected all samples. Magnetic properties are investigated through hysteresis loop analysis at room temperature (RT) and 10 K. M_s (saturation magnetization), M_r (remanence), H_c (coercivity), SQR (squareness ratio), and n_B (experimental magnetic moment), were evaluated as a function of Pd doping. The pristine sample exhibited hard ferrimagnetic behavior with high H_c and M_r, while Pd-doped samples demonstrated reduced magnetic properties. Particularly, intermediate Pd concentrations (x = 0.04 and 0.06) resulted in slight increases in M_s. SQR values signify multi-domain and single-domain nature for Pd-doped and undoped samples, respectively. XPS’ (X-ray photoelectron spectroscopy) broad spectrum of energies verified the presence of Ba, Sr, Pd, Fe, and O in the product.